The Tom Aquarium Products Aqua Lifter is recommended for any application with the CPR Overflow Boxes. The Aqua Lifter will help the Overflow Box to maintain siphon. The Aqua Lifter is a unique one-of-a-kindvacuum pump designed to lift water with its diaphragm and flappers. Note: The Aqua Lifter is not a water circulation pump, it just assists with the siphoning of water out of the tank with an overflow box. You still need a circulation pump to return water to the tank.